Mushroom Identification Tips and Fungal Taxonomy

There are two kinds of folks in this world: people who think dualistically, and people who don’t. My Taoist-Catholic dad shared that goofy little bit of wisdom with me when I had all my mushroom identification books spread out on the floor of his house, desperately trying to cram a few mushrooms I’d found into a genus and species identification that simply was not fitting. I was really flailing around with my dichotomous keys on this particular afternoon, and had gotten pretty frustrated because of an excess of dualistic thinking. It’s not THIS, and it’s not THAT either….what the hell? These books must be broken! These mushrooms must be broken!

Mushroom identification cartoon
What if the tables were turned and the mushrooms identified US? Cartoon in honor of my old home team OMS, drawn by Eriq Geoffrey Nelson.

Mushroom Identification Can Drive a Binary Mind Mad! Dichotomous Keys Help, but They Also Reinforce Dualistic Thinking.

I think this little is paradox about dualism has helped me a great deal in my efforts to improve at mushroom identification, both in keeping my sense of humor, and in reminding myself not to rely too heavily on dichotomous keys for mushroom identification. After all, mushrooms do not exist to please or serve us, and as such all our efforts to organize our knowledge around them can sometimes fail spectacularly.

For those who have never had the pleasure, a dichotomous key is a series of paired statements that describe an organism, and as you proceed through the key, you are able to eliminate certain species and reach a specific mushroom identification by endorsing descriptions that match the mushroom you’re examining.

If That Bit Made No Sense, Here’s A Silly Dichotomous Key!

If you’re so inclined, download this silly little example key and give it a whirl…

Coprinoids
Garden mushrooms! Little coprinoid mushrooms that would be a weensy bit difficult to identify. Photo by Michael Grant.

Anna’s Ridiculous Dichotomous Key

Here is how to use the key. Pick up a ceramic coffee mug or your smartphone and pretend that you are trying to identify it. Read the paired statements in the key, and select the description that best matches your mug or phone. Then, look at the number that is next to the descriptive statement that matches the object you are identifying, and proceed to that number’s paired statements and repeat the process. If you want, you can also use this key to identify such things as dog toys, toilet brushes, and laptop computers. If you decide to use this key to identify a salt-shaker, for instance, you will discover (by way of dramatic and overstated example) one of the limitations of dichotomous keys: there is no salt-shaker on this key, and whether or not it’s hollow can be subjective and thus knock you flat as soon as you start trying to identify it.

As you can clearly see, my dichotomous key is a pretty limited tool (to put it lightly), and although mushroom identification keys are far better constructed, they do have some of the same problems, specifically, what if what you have in your hands does not follow the Choose Your Own Adventure-style path the key wants to take you on? What if the mushroom you are trying to identify is not on the list? What if the mushroom you have collected is an atypical specimen for its species, and thus does not fit within the descriptive statements supplied by the key? What then?!

Mushroom Identification as an Exploratory Process of the Entire Fungal Kingdom

There are lots of good resources in the world for mushroom identification (Pro tip: Wikipedia generally isn’t one of them…although there are exceptions and mining the references can turn up some exceptionally good stuff), and I usually take a blended approach to identifying mushrooms, with my end goal being twofold, with the latter taking precedence:

  1. Identify that weird, unknown mushroom I’ve found.
  2. Learn more about Kingdom Fungi.

By blended approach, I mean that I look at several books, old and new, and harvest information online and from fellow mycophiles, either before or after I have run a mushroom through the dichotomous key. I am fortunate enough to have a pretty good library of older field guides that I’ve scrounged up over the years, some of which are excellent even though many of the Latin names are outdated. I also look at high-confidence collections on Mushroom Observer, peruse the excellent keys and descriptions on Mushroom Expert, and visit other websites to gather data when I am seeking a mushroom identification on a specimen I am not familiar with.

If possible, I also like to consult with one or more of my mycological mentors who can point me in the right direction, especially if I am dealing with one of those “controversial” mushrooms that has numerous Latin names. One thing I love about the mushroom-nerd community is that there are some people who will ALWAYS help with mushroom identification!

Although sometimes this infusion of information sometimes makes me feel like I am getting lost in the weeds of mushroom identification, I am usually more confident if I have used both linear and matrix-based thinking to identify a mushroom. Basically, I attack it from every angle and get as much good information as I can, and even if I never succeed in my mushroom identification, I am bound to learn some new stuff in the process, including traits of genera I am unfamiliar with, which in turn helps strengthen my overall understanding of Kingdom Fungi. This knowledge-harvesting helps me understand not just mushroom identification for one specific species, but a whole range of other facts about fungi that, at the end of the day, gets filed away in the memory bank and often comes quite in handy in the future.

Mushroom Identification Tips

I try to remember Dad’s witticism about dualists whenever I start to climb Mount Taxonomy and play mushroom identification wizard. Of course, the practice of wrangling a feisty species that defies all your expectations into a genus-species box is not a binary, dualistic process. Naming a new species, especially in Kingdom Fungi, is far from a simple delineation of physically obvious traits (morphology). It involves centrifuges, microscopes, and big-ass branchy diagrams (a phylogenetic tree or cladogram are the proper names if you’re into biological genealogy).

Mushroom identification, even with the best books out there, is difficult without considering all the factors at play in the growth and formation of fungi. Sometimes mushroom identification based on morphology (macroscopic features) alone is impossible, due to genetic or microscopic differences between mushroom species that cannot be discovered by simple inspection of a mushroom.

However, do not despair! There are hundreds, if not thousands, of mushrooms that can be identified without a microscope or any other highly specialized equipment/training. Here are just a few of the bits of information I always gather when attempting mushroom identification based on morphology:

  • What trees and plants are nearby? Since many wild mushrooms grow in association with plants, and still others are decomposers that prefer certain types of compost to thrive, knowing what the habitat looked like is critically important to mushroom identification. This is particularly important if you want to post photos to mushroom identification forums and get a clear answer from contributors. Whenever possible, get a picture of several mushrooms in different phases of growth, as well as any nearby flora that your mushroom might be growing in partnership with.
  • What substrate is the mushroom growing in? Mycelium is truly miraculous in its propensity to be opportunivorous, and different mushroom species acquire food using different strategies. Look at what material a mushroom is growing on, and you are looking at the mycelium’s combined home and pantry, and that tells you what the fungus eats, which in turn can be of tremendous help in mushroom identification. Sometimes it’s not completely obvious what the mycelium is growing on, however. Some mushrooms are terrestrial (growing on ground), others grow on wood, and still others can be found in either location. If you find a mushroom on the ground in the forest, however, do not assume it is necessarily growing on in and through the soil. Often, there are buried sticks or stumps that produce mushrooms. The first time I found a chicken of the woods of the species Laetiporus cincinnatus, it was growing on a buried branch and thus appeared to be growing right out of the forest floor. Even though chicken of the woods is very distinctive and almost impossible to misidentify, I almost left it alone because…well…I knew it was a wood decomposing mushroom, and the one I found was on the ground. Another example of a wood-decomposing/parasitic mushroom that may appear terrestrial is the ringless honey mushroom,  Armillaria tabescens. In my yard, it grows in huge clumps where trees used to grow, slowly decomposing the root systems that remain buried underground.
  • What factors could influence the shape, color, and size of the mushroom? Sometimes, mushrooms get seriously deformed by the force of
    bolete with bolete on top
    This rain-washed bolete has a become streaky, and the leaf on its cap looks like…another bolete! Photo by Melissa Sampley.

    something pressing them down on them as they develop. Indeterminate mushrooms like the reishi (Ganoderma lucidum and others), are particularly prone to grow in unusual shapes when there is a bit of wood, a rock, or pine cone in the way. I have one mushroom cultivation buddy who was growing reishi, and he decided to suspend a quartz crystal over the top of his cultivation jar. Lo and behold, as the reishi mushroom fruiting body emerged, it grew right around the crystal, never once making contact with the stone (when I heard this story it made me consider, as always, that the intelligence of mycelium is something we still haven’t begun to fathom. In other words: it blew my freaking mind). Other factors that can change a mushroom’s appearance include leaves that stain their caps, mud and grit that can make them feel slimy when they are not in fact slimy, and of course, rain. Catch some old specimens after a good drizzle and you may be hard-pressed to even begin a proper mushroom identification.

  • What does the mushroom look like underground? To be clear, I do not advocate for digging mushrooms up if you are absolutely sure what they are. For instance, you will never find me digging up chanterelles in the forest, because I know them inside and out and I know what they look like under the surface of the soil, and when I harvest chanterelles I try to do as little damage to the mycelial mat that produced them as possible. However, there are some mushrooms that have a volva (or a sac or cup of tissue that can be quite delicate) at the base of the stem, which sometimes is obscured by dirt. This volva, as well as its shape and character, is critically important in identifying Amanita and Lepiota mushrooms, amongst others. I suggest that you carefully remove the entire mushroom when there is a specimen you wish to identify. Don’t worry too much about the mycelium, just try to be gentle. If you feel guilty about it, just remember that many fungi respond to being disturbed like this with explosive, healthy growth, as long as the mycelium does not sustain catastrophic damage.
  • What does the mushroom smell like? Taste like? Feel like? We human-monkeys are very visual creatures, and so mushroom identification often starts with examining the appearance of a mushroom. However, the fragrance of a mushroom can tell you a lot about its identity. Some mushrooms smell like cedar, others like anise, still others like maple syrup. Lobster mushrooms smell like seafood. Hell, some members of the Inocybe genus smell like semen (this fact always causes some tittering at forays where Inocybes are part of the species collections). You get the idea. Smell your mushrooms. Also, feel them (don’t panic, you can’t hurt yourself by handling even the deadliest mushroom out there!). Is the cap slimy or sticky? Is it smooth or cracked? In addition, the taste of a mushroom can tell you a lot about it. Some mushrooms have a strong peppery taste that’s like cayenne on steroids, especially members of the genera Russula and Lactarius, which are extremely common in North Carolina and contain some very tasty species like Lactarius indigo, Lactarius volemus, and Lactarius corrugis. If you want to taste a mushroom, just chew on a small piece of the cap, then spit it out. Most mushrooms don’t require the taste test for identification, but there are certainly some times that it makes perfect sense to take a nibble and see what you think. Just to clarify, taste testing mushrooms is not for the purpose of ascertaining whether or not it is good to eat – some very tasty mushrooms can make you sick – but many mushroom species contain complex flavorful compounds, and it’s helpful to test for them in some instances!
  • What does the mushroom look like in different phases of growth? I would venture to say that most mushrooms go through a transformation during their growth cycle, and this is why it’s quite helpful to find several specimens that are at different points in that cycle in order to assist you in mushroom identification. If possible, gathering two or three specimens at different points in development can really help you identify wild mushrooms.
  • What do the mushroom’s spores look like? If you are set on learning mushroom identification, taking spore prints is a really good idea. Since mushrooms exist for the sole purpose of propagating fungal DNA, they drop a load of spores that often number in the millions. Different species have unique spore colors, and if you’ve got a microscope, you can put mushroom spores on a slide and examine them even more closely, and you will see even more differences between the spores of the various mushroom species. To take a spore print, simply slice off the cap of a mushroom, place it on a piece of foil, paper, or (my preference) glass, cover it up with a bowl or tupperware, and let it sit for a few hours or overnight. In that time, the mushroom will drop some of its colossal payload of spores, and you can then examine their color. Pro tip: you can also save these spores for making spore slurries and cultivating certain species of mushrooms!

    blue staining bolete
    Some mushrooms stain when the flesh is cut. Boletes like this one stain blue when they oxidize. This specimen stained slowly and slightly over the course of 10 minutes. Other mushrooms stain remarkably fast and dramatically. Photo by Anna McHugh.
  • Does your mushroom stain, bruise, ooze, or react in other ways when you cut or handle it? Lots of mushrooms have wild and dramatic staining reactions, so be on the lookout for bruising, staining, and other changes in the cap, gills, and stem of your mushroom once you handle or collect a specimen. For instance, many members of the genera Boletus and Suillus turn blue, brown, or reddish when they oxidize. Chicken of the woods, when fresh, can drop what feels like a bucket of water on your hand when you cut it. Lactarius mushrooms have gills that bleed colorful, clear, or white milk. Look for these reactions, they are important for mushroom identification, in addition to being really cool!

Of course, this list of mushroom identification tips is not exhaustive, but it is a good start. In future posts, I will address some tips on taking photographs for mushroom identification, because this one area where some people get hung up when they seek outside input over the internet, and there a few great strategies to employ that will greatly increase your chances of getting help with mushroom identification from online groups, forums, and the like.

Just Let the Mushroom Be What it is, Even if That Means You Cannot Identify it!

Sometimes, I simply cannot identify a mushroom that I’ve found, and I have learned over the course of time that this is nothing to worry about or feel troubled by. It used to bother me a lot, and sometimes, my desire for a mushroom to be a particular thing got the better of me and short-circuited my efforts to meaningfully learn about the organism I’d found. Just because I desperately want this mushroom to be a matsutake doesn’t mean that it is. To my way of thinking, that’s just fine; as far as I’m concerned, the mushroom is perfectly welcome not to be a matsutake.

It’s sort of a zen exercise that has enriched my own life to accept that mushrooms do not exist to please me and have no interest in being understood (in fact, sometimes I think they get a huge kick out of being inscrutable). A mushroom is what it is, and if I cannot properly identify it, I can still derive satisfaction from the mystery of its very existence.


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